Mr. Trump's comments came as the Pentagon was still working through the details of how to implement the President's executive actions, as lawmakers waited to see if military construction projects in their home states would be caught up in Pentagon efforts to fund the border wall.
"We write to express concern and opposition to your unilateral decision to reprogram Congressionally approved funding dedicated for critical military construction projects in order to fund a costly and ineffective border wall," wrote lawmakers from New Hampshire in a letter to the President.
"Congress refused to give Trump funding to build his wasteful wall. Instead of listening, he's declared a #FakeTrumpEmergency," wrote Rep. Barbara Lee (D-CA) on Twitter.
President Trump “failed to convince Mexico, the American people or Congress to pay for his massive, misguided border wall,” added Rep. Paul Tonko (D-NY).
“Congress specifically refused to fund the president’s wall at the level he requested & the Constitution does not allow him to overrule Congress when it comes to spending federal dollars,” said Sen. Dianne Feinstein (D-CA).
Meanwhile, Democrats in the House continued to sign on to a resolution which would overturn the President’s national security designation - even before learning the details of where the Trump Administration would get the money from inside the Pentagon.
As for the lawsuits piling up against his executive actions, the President shrugged those off, noting that he had accurately predicted that opponents would file a lawsuit in the Ninth Circuit against his move.
"I was put here for security - whether it's Space Force, which we're doing today, or whether it's borders," Mr. Trump said to reporters.
"Because if our nation doesn't have borders, we don't have too much of a nation," he added.